![]() At Fort Knox, the Re-Os molybdenite date is identical to the U-Pb zircon age for the host intrusion, supporting an intrusive-related origin for the deposit. New Re-Os molybdenite dates from two lode gold deposits of the Tintina Gold Belt, Alaska, provide direct timing constraints for sulfide and gold mineralization. In other cases, several decades may be required before a balance between force and resistance is reached. Landscape stability, which depends on the relationship of the distribution of energy to the material landscape, has been reestablished in some basins in the Central City area. Threshold values of erosive force were surpassed in response to changes in general basin vegetation cover, valley floor vegetation, channel slope, width, and roughness. ![]() ![]() The spatial distribution of energy and force has been substantially altered by human activities. before settlement to 8 dynes during the mining period. ![]() Arroyos and gullies developed on many valley floors as responses to increases in channel tractive force from 1 dyne. Central City is typical of mountain mining towns with clearly defined periods of discovery and settlement, bonanza, investment, development, and, finally, decline. Gold and silver mining activities in the Central City District, Colorado, caused severe disruption of the landscape. ![]()
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